Consider n≥2 pairwise disjoint disks D1,D2,…,Dn on the Euclidean plane. For each k=1,2,…,n, denote by fk the inversion with respect to the boundary circle of Dk. (Here, fk is defined at every point of the plane, except for the center of Dk.) How many fixed points can the transformation fn∘fn−1∘…∘f1 have, if it is defined on the largest possible subset of the plane? geometryanalysiscombinatorial geometry